Dual-wall airfoil with leading edge cooling slot

ABSTRACT

An airfoil including a spar and a cover sheet that are configured for cooling. The spar includes standoffs and a leading edge wall. The standoffs are disposed along a pressure and/or suction side. A pressure-side panel and a suction-side panel are coupled to the standoffs and/or the leading edge wall. Leading ends of the pressure-side panel and the suction-side panel are disposed adjacent to one another proximate to the leading edge. The standoffs extend beyond the pressure-side leading end toward the leading edge wall. At least one of the leading ends of the pressure-side and suction-side panels defines a notch to form an outlet port at the leading edge. Standoffs may be disposed to define grooves in between in communication with the outlet port.

TECHNICAL FIELD

The present disclosure relates generally to gas turbine engines, and more specifically to airfoils used in gas turbine engines.

BACKGROUND

Gas turbine engines are used to power aircraft, watercraft, power generators, and the like. Gas turbine engines typically include a compressor, a combustor, and a turbine. The compressor compresses air drawn into the engine and delivers high pressure air to the combustor. In the combustor, fuel is mixed with the high-pressure air and is ignited. Products of the combustion reaction in the combustor are directed into the turbine where work is extracted to drive the compressor and, sometimes, an output shaft. Leftover products of the combustion are exhausted out of the turbine and may provide thrust in some applications.

Modern gas turbine engines produce high gas temperature environments that are typically above the melting temperature of the internal hardware. In order to survive in these conditions, turbine hardware typically uses a combination of cooling mechanisms to maintain an acceptable temperature. These mechanisms may include film cooling, thermal barrier coatings (TBC), and internal cooling devices. For airfoils, the stagnation point of the leading edge is an area of the highest gas pressure and highest thermal loads. The zone around the stagnation point is therefore a difficult region to cool due to reduced film effectiveness and potential blockage with debris at outlet ports because of the high gas pressure. Film cooling can be costly in terms of stage efficiency, especially in high Mach regions, and large volumes of cooling air are required for present internal cooling devices. Thus, a need exists for improved devices and methods for airfoil cooling.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments may be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale. Moreover, in the figures, like-referenced numerals designate corresponding parts throughout the different views.

FIG. 1 is a perspective view of an example of an airfoil coupled to a pair of endwalls.

FIG. 2 is a perspective view of the airfoil of FIG. 1 without the endwalls, depicting an interior of the airfoil.

FIG. 3 is an exploded assembly view of the airfoil of FIG. 1.

FIG. 4 is a cross-sectional view of the airfoil of FIG. 1.

FIG. 5 is a detail view of a leading edge of the airfoil in FIG. 1.

FIG. 6 is a cross-sectional view taken along line 6-6 in FIG. 4, depicting the arrangement of standoffs and leading edge wall.

FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. 5.

FIG. 8 is a detail view of an example of a notch arrangement of the airfoil in FIG. 1.

FIGS. 9-11 are detail views of examples of notch arrangements, respectively, of the airfoil in FIG. 1.

FIG. 12 is a detail view of a leading edge of another example of an airfoil.

FIG. 13 is a cross-sectional view taken along line 13-13 in FIG. 12.

FIG. 14 is a detail view of a leading edge of another example of an airfoil.

FIG. 15 is a cross-sectional view taken along line 15-15 in FIG. 14.

FIG. 16 depicts a gas turbine engine including an example of an airfoil.

DETAILED DESCRIPTION

Disclosed herein are examples of cooling slot arrangements for dual-wall airfoil configurations. The airfoils may be used in gas turbine engines and combustion systems that may be used in any industry, such as, for example, to power aircraft, watercraft, power generators, and the like. One or more outlet ports are defined by an intersection of a pair of standoffs and a cooling slot. The end of a single or both of the cover sheet panels in the dual-wall airfoil may include notched arrangements such that the ends together form outlet ports along the leading edge. The outlet ports may also be formed by filler material and/or strips as will be described. The cooling slot arrangements in the airfoil may overcome film lifting and improve film cooling at the stagnation point region of the leading edge and direct cooling flow across the cold side and further along the leading edge downstream, such as, for example, toward the pressure side and/or the suction side. The groove arrangement and inlet port configuration may allow for impingement cooling along the interior cover sheet along the stagnation point region of the leading edge. The groove arrangement and inlet port configuration may reduce the pressure losses of the cooling air flow at the outlet ports such that the pressure at the outlet ports is suitable to reduce the risk of debris due to the high gas pressure. The cooling slot arrangements may decrease the flow area at the leading edge of the airfoil when compared with conventional slot designs. The reduced flow area arrangement may require less cooling air flow for purging and improved pressure control for film cooling than with conventional slot designs. Moreover, assembling the cover sheet panels with the cooling slot arrangements to standoffs and walls of the spar may accommodate varying positions of the cover sheet panels relative to the spar. An additional benefit may be to provide a leading edge cooling configuration that is more robust and can be modified for variations in stagnation point locations.

FIG. 1 shows an example of a blade 10 of a gas turbine engine. The blade 10 includes a radially outer endwall 11, a radially inner endwall 13, and an airfoil 12 coupled between the outer and inner endwalls 11, 13. The outer endwall 11 is configured to support a tip 12A of the airfoil 12 between a leading edge 12C and a trailing edge 12D of the airfoil 12, and the inner endwall 13 is configured to support a base 12B of the airfoil 12 between the leading and trailing edges 12C, 12D. Leading edge outlet ports 14 are shown disposed along the leading edge 12C. In an example, the blade 10 is a turbine blade in a turbine section of the gas turbine engine, as described below, and configured to rotate about a central axis of the engine, with the base 12B of the airfoil being in closer proximity to the central axis than the tip 12A. In another example, the blade 10 is part of a static vane assembly in a turbine section of the gas turbine engine, as described below. The blade 10 may include a dovetail-shaped root coupled to the airfoil 12 for connecting the blade 10 to a disk for rotation about a central axis of the engine. As shown in FIG. 2, the airfoil 12 is shaped to define a suction side S and a pressure side P.

With additional reference to FIG. 2, the airfoil 12 includes an internal spar 16 disposed along an airfoil axis AA (FIG. 3) and an external cover sheet 18 coupled to the spar 16, such as metallurgically bonded to the spar 16 or spar features as described below, making the airfoil 12 sometimes referred to as a dual-wall airfoil. In FIG. 3, the airfoil axis AA extends radially perpendicular to the central axis of the engine.

As shown in FIG. 3, the spar 16 may be formed to include a plurality of grooves 20 to define a plurality of cooling passageways disposed between the spar 16 and the cover sheet 18. The grooves 20 are spaced along the spar 16 with standoffs 22 separating the grooves 20. The standoffs 22 protrude outwardly relative to the outer surface 16A of the spar 16 that defines an aspect of the grooves 20. FIG. 3 shows a pattern of grooves 20 in an elongation row configuration extending between the leading edge 12C and the trailing edge 12D and disposed radially spaced from another relative to the central axis and along the airfoil axis AA. The grooves 20 may have other configurations such as portions running in the direction of the tip 12A and/or the base 12B. The cover sheet 18 is coupled to an outer surface 22A of the standoffs 22 with respect to the spar 16 and spaced from the outer surfaces 16A lining the grooves 20, thereby forming the cooling passageways. A flow of cooling air passing through one cooling passageway may be separated from a flow of cooling air passing through an adjacent cooling passageway by the standoffs 22.

FIGS. 2-3 depict the spar 16 including a spar wall 25 defining a body section 26 and a tail section 28 of the spar 16. The spar wall 25 is disposed to define a cooling air plenum 29 along the airfoil axis AA within the hollow spar. The cooling air plenum 29 is adapted to receive a flow of cooling air for delivery to the plurality of grooves 20 via a plurality of inlet ports (shown as inlet ports 30A, 30B, 30C, 30A′, 30B′) defined by the spar wall 25. The flow of cooling air may be supplied through one or more of the outer and inner endwalls 11, 13 of the blade 10. In another example, the flow of cooling air may be supplied through a dovetail-shaped root coupled to the airfoil 12. In an example, the inner endwall 13 includes a central conduit 13A defined therein which is in fluid communication with the cooling air plenum 29 within the airfoil 12. Extending below the inner endwall 13 may be a hollow shank portion (not shown) in communication with the central conduit 13A and coupled to an internal engine passageway for receiving cooling air from the compressor and distributing the cooling air within the cooling air plenum 29 of the airfoil 12.

With reference to FIGS. 3-4, the plurality of grooves 20 may include a plurality of body section grooves 32 and/or a plurality of tail section grooves 34. As may be appreciated by one of ordinary skill in the art, the grooves 32, 34 are shown being formed in the suction side S of the spar 16 (will now be referred with “S” following the reference numeral), may also be formed in the pressure side P of the spar 16 (will now be referred with “P” following the reference numeral), as shown in FIG. 6.

A first trailing separator wall 33A may be disposed along the suction side S between the body section grooves 32S and the tail section grooves 34S such that a flow of cooling air passing through the body section grooves 32S is separated from a flow of cooling air passing through the tail section grooves 34S. A second trailing separator wall 33B may be disposed along the pressure side P between the body section grooves 32P and the tail section grooves 34P such that a flow of cooling air passing through the body section grooves 32P is separated from a flow of cooling air passing through the tail section grooves 34P. The tail section grooves 34S extend between a first tail portion 30A of the inlet ports and an exit slot 35, downstream of the first tail portion inlet ports 30A. The tail section grooves 34P extend between a second tail portion 30A′ of the inlet ports and a trailing outlet slot 35′, downstream of the second tail portion inlet ports 30A′. The exit slot 35 and/or the trailing outlet slot 35′ may be defined between the spar 16 and the cover sheet 18.

The standoffs 22 are shown having elongated shape to define elongate channels. The standoffs 22 defining the body section grooves 32S and/or 32P and the tail section grooves 34S and/or 34P may have other configurations than illustrated in the figures. For example, the standoffs 22 may comprise a plurality of pedestals, columns, or pins or combination of variously sized elongated members and/or pedestals, columns, or pins. The pedestals, columns or pins may have various cross-sectional shapes, including rectangular, diamond, circular or semi-circular, as well as other shapes.

The body section grooves 32S extend between a first body portion 30B of the inlet ports and to a plurality of first body portion outlet ports 17, which are upstream of the first body portion inlet ports 30B. The first body portion outlet ports 17 are defined by the suction-side panel 40 along the leading edge. The first body portion outlet ports 17 may be oriented toward the suction side to provide film cooling along the airfoil surface. An intermediate portion corresponding to cooling passageways CP2 defined by the body section grooves 32P to provide cooling along the outside boundary of the panel. The body section grooves 32P extend between a second body portion 30B′ of the inlet ports and to a plurality of second body portion outlet ports 37, which are upstream of the second body portion inlet ports 30B′. A gap G may be formed in the standoffs 22 and/or the separator walls 33A, 33B, 33C to allow the flows of cooling air in the grooves to transfer between the adjacent respective grooves. The body section grooves 32S extend between the first body portion inlet ports 30B and an outlet-port plenum 17P disposed along a leading edge wall 39 where the flow of cooling air is distributed to the first body portion outlet ports 17 formed through the suction-side panel 40 as shown in FIG. 4.

A leading separator wall 33C may be disposed to divide the body section grooves 32P into further groove arrays, as illustrated. The leading separator wall 33C may be disposed to divide the body section grooves 32S into further groove arrays. The leading separator wall 33C may be disposed away from the leading edge wall 39 in a pressure side direction to divide the body section grooves 32P into a plurality of body section leading grooves 32L that is closer in proximity to the leading edge than an plurality of body section grooves 32P that is closer in proximity to the trailing edge. The body section leading grooves 32L extend between a third body portion 30C of the inlet ports and to the leading edge outlet ports 14, which are upstream of at least a portion of the third body portion inlet ports 30C. FIG. 3 depicts the leading edge wall 39 defined between the body section grooves 32P of the pressure side P and the body section grooves 32S of the suction side S. The separator walls 33A, 33B and/or 33C and/or the leading edge wall 39 may protrude at a similar distance as the standoffs 22 and axially extend along the airfoil axis AA at least partially, and in some examples, fully, from the base 12B and to the tip 12A.

The stagnation point SP may be located along any point of the leading edge 12C. To this end, the leading edge outlet ports 14 are shown disposed along the pressure side P, but may be disposed along the suction side S or closer to the center of the leading edge 12C. The leading edge wall 39 may be disposed at the suction side with the body section grooves 32L extending from the pressure side and across the center of the leading edge to the suction side. Alternatively, the leading separator wall 33C may be disposed to divide the body section grooves 32S into further groove arrays. The leading separator wall 33C may be disposed away from the leading edge wall 39 in a suction side direction to divide the body section grooves 32S into the plurality of body section leading grooves 32L that is closer in proximity to the leading edge than the plurality of body section grooves 32S that is closer in proximity to the trailing edge. Like the body section leading grooves 32L shown in FIG. 6, the grooves 32L formed at the suction side may extend between the third body portion 30C of the inlet ports and to the leading edge outlet ports 14.

The cooling passageways may be sized to define microchannels. For example, a width W of the grooves 20 is defined between adjacent standoffs 22 as representatively shown by body section grooves (such as grooves 34P, 32P, 32L in FIG. 6). In an example, the width W of the grooves 20 may be 0.02 inches, 0.05 inches, or any size therebetween. Similarly, a height H of the grooves 20 or depth of the cooling passageways is defined between the spar 16 and the cover sheet 18, as shown in FIG. 7. In one example, the height H of the grooves 20 is 0.015 inches, 0.035 inches, or any size therebetween. A length L of the standoffs 22 is defined across the spanning width of the standoffs in the same direction as the width W of the grooves.

The standoffs 22 defining the grooves 20 may include at least one turbulator 36. The use of turbulators 36 enables increased cooling performance by facilitating the mixing of cooling air flow and reducing the amount of cooling air needed to cool the blade 10. The grooving facing surfaces 38 form the upright walls of the standoffs 22. The turbulators 36 are shown disposed along grooving facing surfaces 38 of the standoffs 22 and extending away from the groove facing surfaces 38 into the regions of the grooves 20. In one example, in addition to or instead of the outwardly extending turbulators, the turbulators 36 may also be formed as recesses, or inwardly facing, formed into the groove facing surfaces 38 of the spar 16. The extension or recess of the turbulators 36 may be 0.003 inches, 0.007 inches, or any size therebetween.

In FIGS. 2-3, the cover sheet 18 is shown including a suction-side panel 40 and a pressure-side panel 42. The suction-side panel 40 may be coupled to the outer surface 22A of the standoffs 22 of the suction side S of the spar 16 to at least partially cover the grooves 32, 34 for defining the cooling passageways. Similarly, the pressure-side panel 42 may be coupled to the outer surface 22A of the standoffs 22 at the pressure side P of the spar 16. The panels 40, 42 may be a thin walled member, having a wall thickness in the range, such as, for example, about 0.015 inches to 0.025 inches. The pressure-side panel 42 and the suction-side panel 40 may be arranged relative to one another to define a leading edge slot 50 therebetween, as shown in FIGS. 1-2. The standoffs 22 may be extended beyond a leading end 52 of the pressure-side panel 42 toward the leading edge wall. The standoffs 22 may transverse the leading edge slot 50 and extend to the leading edge wall. This intersection of the leading edge slot 50 by the standoffs 22 define the boundary of the leading edge outlet ports 14 between the standoffs 22 and ends of the panels 40, 42.

With additional reference to FIGS. 5 and 7, the leading end 52 of the pressure-side panel 42 may be arranged adjacent to a confronting leading end 56 of the suction-side panel 40. In one example, the leading end 52 of the pressure-side panel 42 and the leading end 56 of the suction-side panel 40 are in a contacting relationship. In another example, the leading end 52 of the pressure-side panel 42 and the leading end 56 of the suction-side panel 40 may be spaced from one another by a distance D. The distance D shown between the panels in the figures is for illustrative purpose and should not be limiting. The distance D may be based on the desired mount of air flow needed. The distance D may also accommodate thermal expansion of the panels and/or manufacturing assembly tolerances. The leading end 52 and the leading end 56 may be beveled at an angle A as shown in FIG. 7. The beveling of the leading ends 52, 56 may orient the leading edge outlet ports 14 in a desired direction. For example, the direction may be toward the pressure-side to provide film cooling along the airfoil surface at a leading edge pressure side zone LEP. The LEP zone may be defined between the stagnation point SP and the second body portion outlet port 37 along the pressure-side. Of course, when cooling is desired between the stagnation point SP and the suction side, a similar leading edge pressure side zone may also be defined. For example, the desired direction from the beveled leading ends may be toward the pressure-side and/or the suction-side, and/or radially along the slot in the direction toward the airfoil tip and/or the airfoil base, or any combination thereof to provide film cooling along the airfoil surface. Body section leading grooves 32L are disposed across the LEP zone between the leading separator wall 33C and the leading edge wall 39.

The leading end 52, the leading end 56, or both, may have a notched arrangement to define aspects of the leading edge outlet ports 14 along the leading edge slot 50. In an example, the pressure-side panel 42 includes a series of first notches 60 defined in the leading end 52, and the suction-side panel 40 includes a series of second notches 62 defined in the leading end 56. Each of the first notches 60 may be radially spaced from the adjacent first notch by a series of first bridges 64. Each of the second notches 62 may be radially spaced from the adjacent second notch by a series of second bridges 66. The leading edge outlet ports 14 are defined by at least one of the first notches 60 and at least one of the second notches 62. In an example, a pair of confronting first and second notches 60, 62 defines one of the leading edge outlet ports 14. For example, the first and second notches 60A, 62A are disposed across the leading edge slot 50 from one another in a confronting and aligned relationship. To this end, the first bridges 64 and the second bridges 66 may be sized accordingly to place the first and second notches 60, 62 across from one another. The size of the first and second bridges 64, 66 is shown as being a constant size. In alternative examples, the size of the first and second bridges 64, 66 may vary in size so long as the first and second notches 60, 62 are disposed across from another. The depth of the first and second notches 60, 62 that define the leading edge outlet ports 14 have a spacing S in between the notches that is greater than the distance D. The distance D between the panels may be minimal such that the leading end 52 and the leading end 56 of the panels may be adjacent to one another. The leading ends 52, 56 may be adjacent to one another in a contacting relationship or spaced from one another by the distance D up to 0.02 inches or more. Alternatively, the leading ends 52, 56 may be coupled to one another to form an overlapping lap joint.

FIG. 6 is a side view of the spar 16 at the pressure side, with the pressure-side panel 42 and the suction-side panel 40 of the cover sheet 18 removed. The standoffs 22 are shown as discrete and extending to the leading edge wall 39 to separate the flow of cooling air in adjacent body section leading grooves 32L. In an example, the standoffs 22 are disposed radially from another relative to the central axis of the engine, extending in a direction transversing the axial direction of the leading edge wall 39 and the separator walls 33B, 33C. The transverse direction includes a direction orthogonal to the airfoil axis AA as well as up to 45 degrees relative to the airfoil axis. Third body portion 30C of the inlet ports are shown defined in the outer surface 16A disposed between the standoffs 22 where the body section leading grooves 32L are located. In an example, each of the standoffs 22 includes a leading end 68 coupled to the standoffs 22.

Turning back to FIG. 5, the leading edge outlet ports 14 are shown disposed in an overlapping relationship with the body section leading grooves 32L. In other words, the first notches 60 and the second notches 62 are shown overlapping the body section leading grooves 32L. The first and second bridges 64, 66 are shown overlapping the standoffs 22. In an example, the first and second bridges 64, 66 may have a length corresponding to the length L of the respective standoffs 22. The suction-side panel 40 may be disposed extending beyond the leading edge wall 39 in the pressure side P direction to define an overhang portion 67. In this manner, the suction-side panel 40 may be coupled to the respective outer surfaces of the leading edge wall 39 and a portion of the standoffs 22 along the suction side. The pressure-side panel 42 may be disposed spaced from the leading edge wall 39 and coupled to the outer surfaces of the standoffs 22 along the pressure side. The leading edge outlet ports 14 are shown being sized to span the width W of the grooves. Alternatively, the leading edge outlet ports 14 may be sized smaller than the width W or larger than the width W. Alternatively, more than one leading edge outlet ports 14 may occupy the width of a single groove.

FIG. 7 illustrates a cross-sectional view of FIG. 5 taken along lines 7-7, depicting the relative distance between the spar 16 and the pressure-side panel 42 and the suction-side panel 40 of the cover sheet 18. The panels 40, 42 of the cover 18 are shown disposed over the body section leading grooves 32L for defining the cooling passageways CP in fluid communication with the leading edge outlet ports 14 and the third body portion 30C of the inlet ports. The flow of cooling air is delivered from the cooling air plenum 29 to the body section leading grooves 32L via the third body portion 30C of the inlet ports for cooling impingement against the pressure-side panel 42 of the cover sheet 18. The flow of cooling air then travels down the body section leading grooves 32L and exits the body section leading grooves 32L via the leading edge outlet ports 14 at the leading edge slot 50.

The number of third body portion 30C of the inlet ports along each of the body section leading grooves 32L may be one, two, three (shown) or more. Additional inlet ports may provide better distribution of impingement cooling of the cover sheet. FIG. 4 illustrates all of the third body portion 30C of the inlet ports located upstream of the location of the leading edge outlet ports 14 such that the cooling air flow runs upstream to exit the leading edge outlet ports 14. Alternatively, the location of the leading edge outlet ports 14 may be disposed between adjacent third body portion 30C of the inlet ports such that the cooling air flow runs upstream and downstream to exit the leading edge outlet ports 14. The body section leading grooves 32L may also be referred to as microchannels, which may not include any turbulators. The body section leading grooves 32L may be configured as a linear path to minimize the pressure losses of the flow of cooling air within the grooves. To this end, there is minimal pressure drop from the flow of cooling air within the plenum to the leading outlet ports. A higher pressure cooling air at the leading outlet ports may reduce the potential for high gas ingestion into the airfoil and the potential for debris into the airfoil through the leading outlet ports, thereby improving the cooling efficiency along the leading edge at the leading edge pressure side zone LEP. A higher pressure cooling air at the leading outlet ports may increase the film cooling downstream of the leading outlet ports along the leading edge at the leading edge pressure side zone LEP.

FIG. 8 depicts an example shape of the first notch 60 and an example shape of the second notch 62. The first notch 60 may be defined by three walls: a first wall 71, a second wall 72, and a third 73. The first and third walls 71, 73 may be inclined toward the second wall 72 that is disposed at a first depth L1 from the leading end 52 to define a tapered notch. The second wall 72 may be in parallel with the leading end 52. The second notch 62 may be defined by three walls: a first wall 81, a second wall 82, and a third 83. The first and third walls 81, 83 may be inclined toward the second wall 82 that is disposed at a second depth L2 from the leading end 56 to define a tapered notch. The second wall 82 may be in parallel with the leading end 56. FIG. 9 depicts another example shape of the first notch (now referred to as 160) and another example shape of the second notch (now referred to as 162). The first and third walls 171, 173 defining a portion of the first notch 160 may be substantially orthogonal (90+/−5 degrees) with the second wall 172 defining another portion of the first notch 160 that is disposed at the first depth L1 from the leading end 52 to define a rectangular notch. The first and third walls 181, 183 defining a portion of the second notch 162 may be substantially orthogonal (90+/−5 degrees) with the second wall 182 defining another portion of the second notch 162 that is disposed at the second depth L2 from the leading end 56 to define a rectangular notch. The notches 160, 162 are shown disposed over the channels defined by the standoffs 22 (shown in cross-hatched) that extend underneath the gap. FIG. 10 depicts another example shape of the first notch (now referred to as 260) and another example shape of the second notch (now referred to as 262). The wall 270 defining the first notch 260 may be arcuate to define a rounded notch at the first depth. The wall 280 defining the second notch 262 may be arcuate to define a rounded notch at the second notch. The notches 260, 262 may also include linear walls in addition to the arcuate wall. The notches 260, 262 are shown disposed over the channels defined by the standoffs 22 (shown in cross-hatched) that extend underneath the gap.

The shape and configuration of the notches may be other geometric or irregular shapes, such as a scalloped shape. The second depth L2 of the notches describe herein may coincide to the amount or length X of the overhang portion 67 of the suction-side panel 40 extending beyond the leading edge wall 39 to place the second wall 72 or arcuate tip at the edge of the leading edge wall 39. In other examples, the second depth L2 may place the second wall 72 or arcuate tip short of the leading edge wall 39 or covering the leading edge wall 39. The second depth L2 may be the same depth as the first depth L1, such as shown in FIGS. 9-10. In an example, the second depth L2 may be less than the first depth L1, as shown in FIG. 8. In FIG. 8, the width of the second wall 72 may be longer than the width of the second wall 82, or may be the same length as suggested in FIG. 9.

In an alternative example shown in FIG. 11, the leading end 56 of the suction-side panel 40 may not be notched and only the leading end 52 of the pressure-side panel 42 may have the notched arrangement to define the leading edge outlet ports 14 along the leading edge slot 50. To this end, the suction-side panel 40 does not include notches defined in the leading end 56, and the pressure-side panel 42 includes notches 360 defined in the leading end 52. Here, the notches 360 may be shaped similar to what is described herein or may have other shapes. The flow of cooling air would exit the cooling air passageways via the leading outlet ports defined by the notches 360.

FIGS. 12-13 depict another example of the airfoil (referred to now as 412). The standoffs 22 are extended to and coupled to the leading edge wall 39. The leading edge outlet ports 414 are defined by an intersection of a pair of adjacent standoffs 22 and the leading edge slot 450, and are in communication with the cooling passageway. The suction-side panel 440 may be coupled to the outer surface of the standoffs 22 of the suction side S of the spar 16 to at least partially cover the body section leading grooves 32L for defining the cooling passageways. Similarly, the pressure-side panel 442 may be coupled to the outer surface 22A of the standoffs 22 at the pressure side P of the spar 16. The pressure-side panel 442 and the suction-side panel 440 are arranged relative to one another to define the leading edge slot 450. A plurality of strips 480 may be coupled along the panels 440, 442. In one example, the leading end 452 of the pressure-side panel 442 and the leading end 456 of the suction-side panel 440 may have recesses 470, 472 (in FIG. 13) formed therein, respectively, that are sized and shaped to receive one or more strips 480. The recesses 470, 472 may be formed from the respective leading ends and into the panel. Here, the strips 480 may be inset within the recesses 470, 471 and securely coupled therein, such that the outer surfaces of the strips 480 and the panels 440, 442 form a smooth surface configured for suitable cooling and flow along the surfaces. Alternatively, the recesses 470, 472 may be formed on the underneath surface of the panels such that the strips may be disposed along the inside of the panels instead of the outside as shown. Alternatively, the strips may be extended from or attached to the spar. The strips 480 may be disposed radially away from one another along the standoffs 22. The spacing between the strips 480 and the panels 440, 442 defines the edges of the leading edge outlet ports 414. The distance between adjacent strips 480 may be less than the width W of the body section leading grooves 32L in order to define smaller outlet ports, which can be interposed along the airfoil at strategic locations. The radial edges 481, 482 of the strips 480 may be linear as shown, or may be contoured or otherwise notches to define the leading edge outlet ports 414 in non-rectangular shapes. FIG. 13 depicts the flow of cooling air delivered from the cooling air plenum to the body section leading grooves 32L via the third body portion 30C of the inlet ports defined by the spar wall for impingement against the cover sheet. The flow of cooling air then travels down the body section leading grooves 32L and exits the grooves via the leading edge outlet ports 414. The strips 480 may be formed from a metallic material, such as high-temperature resistant alloy, a ceramic material, such as a ceramic-matrix composite material, or other materials. The strips 480 may be attached via soldering or welding in a manner to withstand the pressure and temperature of the engine environment.

FIGS. 14-15 depict another example of the airfoil (referred to now as 512). The leading edge outlet ports 514 are defined by an intersection of a pair of adjacent standoffs 22 and the leading edge slot 550, and are in communication with the cooling passageway. The standoffs 22 are extended to and coupled to the leading edge wall 39. The suction-side panel 540 may be coupled to the outer surface of the standoffs 22 of the suction side S of the spar 16 to at least partially cover the body section leading grooves 32L for defining the cooling passageways. Similarly, the pressure-side panel 542 may be coupled to the outer surface 22A of the standoffs 22 at the pressure side P of the spar 16. The pressure-side panel 542 and the suction-side panel 540 are arranged relative to one another to define the leading edge slot 550. A plurality of filler material 580 may be coupled, such as metallurgically bonded, along the outside of the standoffs 22 within the zone defined by the leading edge slot 550. The filler material 580 may be extended beyond the edges of the standoffs 22 to modify the cross-sectional area of the leading edge outlet ports 514. The filler material 580 may be disposed radially away from one another at locations corresponding with the standoffs 22. The spacings between the locations of the filler material 580 and the panels 540, 542 define boundaries of the leading edge outlet ports 514. FIG. 15 depicts the flow of cooling air delivered from the cooling air plenum to the body section leading grooves 32L via the third body portion 30C of the inlet ports defined by the spar wall for impingement against the cover sheet. The flow of cooling air then travels down the body section leading grooves 32L and exits the grooves via the leading edge outlet ports 514. The filler material 580 may be formed from a metallic material, such as high-temperature resistant alloy, a ceramic material, such as a ceramic-matrix composite material, or other materials such as used for soldering or welding.

Referring to FIG. 16, there is illustrated a gas turbine engine 620 which includes a compressor 621, a combustor 622 and a power turbine 623. The three components have been integrated together to produce an aircraft flight propulsion engine. The term aircraft is generic and includes helicopters, airplanes, missiles, unmanned space devices and any other substantially similar devices. There are a multitude of ways in which the gas turbine engine components can be linked together. Additional compressors and turbines could be added with intercoolers connecting between the compressors and reheat combustion chambers could be added between the turbines. Further, the gas turbine engine is equally suited to be used for an industrial application. Historically, there has been widespread application of industrial gas turbine engines, such as pumping sets for gas and oil transmission lines, electricity generation and naval propulsion.

A plurality of turbine blades 624 are coupled to a rotor disk that is affixed to a shaft rotatable within the gas turbine engine 620. A plurality of vanes 625 are conventionally joined together to collectively form a complete 360-degree nozzle. It is understood herein that gas turbine engine blades and vanes are often referred to as airfoils, such as the airfoils 12, 412, 512. Other products utilizing the airfoils are contemplated herein including but not limited to combustor liners, exhaust nozzles, exhaust liners, airframe wing leading edges, and/or other actively cooled components. The compressor 621 provides cooling air to the cooling air plenum 29 of the airfoils 12, 412, 512 through the internal engine passageway leading from the compressor to the power turbine 623, and traversing the hollow shank portion, the central conduit 13A of the inner endwall 13 and into the airfoil. The cooling air may be a compressible fluid such as air.

In one example, the airfoils 12, 412, 512 of the gas turbine engine and its components are formed of a heat resistant superalloy composition, a ceramic material, such as a ceramic-matrix composite (CMC) material, or other materials used for components. There are various types of superalloy compositions, such as but not limited to nickel based or cobalt based compositions, and the manufacturers of such compositions are generally known to those skilled in the art. Most superalloy compositions of interest are complicated mixtures of nickel, chromium, aluminum and other select elements. The airfoils may be of a unitary cast configuration, and/or an assembly of cast components, and/or an assembly of cast and wrought components. The airfoils may have an equiax, directionally solidified or a single crystal alloy structure. In one example, the airfoil is of a cast single crystal single structure. Further, in alternate examples of the present invention the products are formed of a metallic material, or an intermetallic material or a ceramic material. In one example, the spar is formed through a casting process to form the standoffs that line the boundaries of the plurality of grooves or channels. In another example, the spar is machined to form the standoffs and the plurality of grooves or channels. In another example, the spar and the cover sheet are integrally formed with one another, with the standoffs walls and the plurality of grooves or channels formed between the spar and the cover sheet. In another example, the airfoil is formed as a unitary component through a casting or 3-D printing process, for example.

The cooling passageways or cooling microchannels run below the airfoil surface to transport cooling air to one or more film outlet ports or slot at the leading edge. Impingement inlet ports may be positioned along the length of the channel. The channels shape, impingement hole location/quantity, and turbulator location/quantity may be configured to maintain the desired cooling flow rate and heat transfer over the entire length of the channel. The film outlet ports or slot may be configured to reduce the aerodynamic penalty and further reduce surface temperatures. Embedding the channels below the airfoil surface allows for higher cooling effectiveness. Coolant air enters the cooling channel and flows along the smooth surface.

To clarify the use of and to hereby provide notice to the public, the phrases “at least one of <A>, <B>, . . . and <N>” or “at least one of <A>, <B>, . . . <N>, or combinations thereof” or “<A>, <B>, . . . and/or <N>” are defined by the Applicant in the broadest sense, superseding any other implied definitions hereinbefore or hereinafter unless expressly asserted by the Applicant to the contrary, to mean one or more elements selected from the group comprising A, B, . . . and N. In other words, the phrases mean any combination of one or more of the elements A, B, . . . or N including any one element alone or the one element in combination with one or more of the other elements which may also include, in combination, additional elements not listed.

The subject-matter of the disclosure may also relate, among others, to the following aspects:

1. An airfoil for use in a gas turbine engine and having a pressure side, a suction side, and a leading edge, the airfoil comprising: a spar including a plurality of standoffs and a leading edge wall extending away from an outer surface of the spar, the leading edge wall disposed along a leading edge; a suction-side panel coupled to the leading edge wall; a pressure-side panel coupled to at least a portion of the standoffs, a leading end of the pressure-side panel and a leading end of the suction-side panel disposed adjacent to one another proximate to the leading edge, wherein the standoffs extend beyond the leading end of the pressure-side panel toward the leading edge wall, wherein at least one of the leading end of the pressure-side panel and the leading end of the suction-side panel defines a notch.

2. An airfoil for use in a gas turbine engine and having a pressure side, a suction side, and a leading edge, the airfoil comprising: a spar including a plurality of standoffs and a leading edge wall extending away from an outer surface of the spar, the leading edge wall disposed along a leading edge, the standoffs disposed spaced radially from another to define an plurality of grooves along a pressure side; a suction-side panel coupled to the leading edge wall; a pressure-side panel coupled to at least a portion of the standoffs to define a plurality of cooling passageways between the pressure-side panel and the outer surface of the spar along the respective grooves, a leading end of the pressure-side panel and a leading end of the suction-side panel arranged relative to one another to define a leading edge slot at the leading edge, wherein the standoffs transverse the leading edge slot and are coupled to the leading edge wall, wherein at least one of the leading end of the pressure-side panel and the leading end of the suction-side panel defines a series of notches in communication with the cooling passageways.

3. A gas turbine engine, comprising: a compressor, a combustor, and a turbine section, wherein the turbine section includes a dual wall airfoil comprising a spar and a cover sheet, the spar including a cooling air plenum disposed along an airfoil axis, the cooling air plenum arranged to receive cooling air from the compressor, the airfoil having a pressure side, a suction side, a leading edge, and a trailing edge, the spar having including a plurality of standoffs along a pressure side, a leading edge wall, and a leading separator wall each extending away from an outer surface of the spar, the leading edge wall and the leading separator wall extending in a direction along an airfoil axis, the standoffs extending in a direction transversing the leading edge wall and the leading separator wall, the leading separator wall disposed away from the leading edge wall in a direction of the pressure side, wherein a portion of the spar defines an inlet port in communication with the cooling air plenum, a suction-side panel coupled to the leading edge wall, the suction-side panel including a leading end, and a pressure-side panel coupled to the standoffs, the pressure-side panel including a leading end, the leading end of the pressure-side panel and the leading end of the suction-side panel arranged relative to one another to define a leading edge slot, wherein an outlet port is defined by an intersection of a pair of the standoffs and the leading edge slot, the outlet port in communication with the inlet port.

4. The airfoil of any of aspects 1 to 3, wherein the standoffs are disposed spaced radially from another to define a plurality of grooves along a pressure side, wherein the notch is disposed over and in communication with only one of the grooves.

5. The airfoil of any of aspects 1 to 4, wherein the notch is defined by the leading end of the pressure-side panel.

6. The airfoil of any of aspects 1 to 5, wherein the leading end of the pressure-side panel defines another notch in communication with another of the grooves, the another notch radially spaced from the notch by a bridge, the bridge being disposed over a length of the respective standoff in between the corresponding grooves.

7. The airfoil of any of aspects 1 to 6, wherein the notch is a first notch, and the leading end of the pressure-side panel defines a series of first notches, and the leading end of the suction-side panel defines a series of second notches, one of the first notches and one of the second notches are aligned across from each other to form a pair of first and second notches in communication with one of the grooves.

8. The airfoil of any of aspects 1 to 7, wherein the leading end of the suction-side panel is disposed extending beyond the leading edge wall in a direction of the pressure side to define an overhang portion, wherein the standoffs extend beyond the leading end of the pressure-side panel and the leading end of the suction-side panel to the leading edge wall.

9. The airfoil of any of aspects 1 to 8, wherein the standoffs are disposed spaced radially from another to define an plurality of grooves along a pressure side, wherein the notch is a first notch, and the leading end of the pressure-side panel defines a series of first notches disposed over and in communication with the corresponding grooves, and the leading end of the suction-side panel defines a series of second notches disposed over and in communication with the corresponding grooves, one of the second notches having a second notch depth that coincides with a length of the overhang portion.

10. The airfoil of any of aspects 1 to 9, wherein one of the second notches has a second notch depth that is less than a first notch depth of one of the first notches.

11. The airfoil of any of aspects 1 to 10, wherein the series of notches comprises a series of first notches defined by the leading end of the pressure-side panel, and a series of second notches defined by the leading end of the suction-side panel, one of the first notches and one of the second notches are aligned across from one another to form a pair of first and second notches in communication with one of the cooling passageways.

12. The airfoil of any of aspects 1 to 11, wherein the leading end of the suction-side panel is disposed extending beyond the leading edge wall in a direction of the pressure side to define an overhang portion.

13. The airfoil of any of aspects 1 to 12, wherein the second notches are defined having a second notch depth that coincides with a length of the overhang portion.

14. The airfoil of any of aspects 1 to 13, wherein the first notches are defined having a first notch depth that is greater than the second notch depth of the second notches.

15. The airfoil of any of aspects 1 to 14, wherein each of the first notches are spaced from another and each of the second notches are spaced from another by bridges.

16. The airfoil of any of aspects 1 to 15, wherein each of the bridges are disposed over a length of the respective standoff in between the corresponding cooling passageways.

17. The airfoil in any of aspects 1 to 16, wherein the standoffs are disposed radially from another to define an plurality of grooves along the pressure side, wherein the grooves are divided by the leading separator wall into an plurality of body section leading grooves closer in proximity to a leading edge and an plurality of body section grooves closer in proximity to a trailing edge, wherein the inlet port is defined by a portion of the spar along one of the body section leading grooves, wherein a portion of the spar along one of the body section grooves defines a body portion inlet port in communication with the cooling air plenum.

18. The airfoil in any of aspects 1 to 17, wherein a filler material is coupled to an outer surface of the standoffs in the leading edge slot.

19. The airfoil in any of aspects 1 to 18, wherein a pair of strips is coupled to the pressure-side panel and the suction-side panel, extending across the leading edge slot.

20. The airfoil in any of aspects 1 to 19, wherein the leading end of the pressure-side panel defines a first notch, and the leading end of the suction-side panel defines a second notch, the first notch and the second notch being arranged to define an aspect of the outlet port.

While various embodiments have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible. Accordingly, the embodiments described herein are examples, not the only possible embodiments and implementations. Furthermore, the advantages described above are not necessarily the only advantages, and it is not necessarily expected that all of the described advantages will be achieved with every embodiment. 

What is claimed is:
 1. An airfoil for use in a gas turbine engine and having a pressure side, a suction side, and a leading edge, the airfoil comprising: a spar including a plurality of standoffs and a leading edge wall extending away from an outer surface of the spar, the leading edge wall disposed along the leading edge; a suction-side panel coupled to the leading edge wall; a pressure-side panel coupled to at least a portion of the standoffs, a leading end of the pressure-side panel and a leading end of the suction-side panel disposed adjacent to one another proximate to the leading edge, wherein the standoffs extend beyond the leading end of the pressure-side panel toward the leading edge wall, wherein at least one of the leading end of the pressure-side panel and the leading end of the suction-side panel defines a notch.
 2. The airfoil of claim 1, wherein the standoffs are disposed spaced radially from another to define a plurality of grooves along a pressure side, wherein the notch is disposed over and in communication with only one of the grooves.
 3. The airfoil of claim 2, wherein the notch is defined by the leading end of the pressure-side panel.
 4. The airfoil of claim 3, wherein the leading end of the pressure-side panel defines another notch in communication with another of the grooves, the another notch radially spaced from the notch by a bridge, the bridge being disposed over a length of the respective standoff in between the corresponding grooves.
 5. The airfoil of claim 3, wherein the notch is a first notch, and the leading end of the pressure-side panel defines a series of first notches, and the leading end of the suction-side panel defines a series of second notches, one of the first notches and one of the second notches are aligned across from each other to form a pair of first and second notches in communication with one of the grooves.
 6. The airfoil of claim 1, wherein the leading end of the suction-side panel is disposed extending beyond the leading edge wall in a direction of the pressure side to define an overhang portion, wherein the standoffs extend beyond the leading end of the pressure-side panel and the leading end of the suction-side panel to the leading edge wall.
 7. The airfoil of claim 6, wherein the standoffs are disposed spaced radially from another to define a plurality of grooves along a pressure side, wherein the notch is a first notch, and the leading end of the pressure-side panel defines a series of first notches disposed over and in communication with the corresponding grooves, and the leading end of the suction-side panel defines a series of second notches disposed over and in communication with the corresponding grooves, one of the second notches having a second notch depth that coincides with a length of the overhang portion.
 8. The airfoil of claim 7, wherein one of the second notches has a second notch depth that is less than a first notch depth of one of the first notches.
 9. An airfoil for use in a gas turbine engine and having a pressure side, a suction side, and a leading edge, the airfoil comprising: a spar including a plurality of standoffs and a leading edge wall extending away from an outer surface of the spar, the leading edge wall disposed along the leading edge, the standoffs disposed spaced radially from another to define a plurality of grooves along a pressure side; a suction-side panel coupled to the leading edge wall; a pressure-side panel coupled to at least a portion of the standoffs to define a plurality of cooling passageways between the pressure-side panel and the outer surface of the spar along the respective grooves, a leading end of the pressure-side panel and a leading end of the suction-side panel arranged relative to one another to define a leading edge slot at the leading edge, wherein the standoffs transverse the leading edge slot and are coupled to the leading edge wall, wherein at least one of the leading end of the pressure-side panel and the leading end of the suction-side panel defines a series of notches in communication with the cooling passageways.
 10. The airfoil of claim 9, wherein the series of notches comprises a series of first notches defined by the leading end of the pressure-side panel, and a series of second notches defined by the leading end of the suction-side panel, one of the first notches and one of the second notches are aligned across from one another to form a pair of first and second notches in communication with one of the cooling passageways.
 11. The airfoil of claim 10, wherein the leading end of the suction-side panel is disposed extending beyond the leading edge wall in a direction of the pressure side to define an overhang portion.
 12. The airfoil of claim 11, wherein the second notches are defined having a second notch depth that coincides with a length of the overhang portion.
 13. The airfoil of claim 12, wherein the first notches are defined having a first notch depth that is greater than the second notch depth of the second notches.
 14. The airfoil of claim 10, wherein each of the first notches is spaced from another and each of the second notches are spaced from another by bridges.
 15. The airfoil of claim 14, wherein each of the bridges are disposed over a length of the respective standoff in between the corresponding cooling passageways.
 16. A gas turbine engine, comprising: a compressor, a combustor, and a turbine section, wherein the turbine section includes a dual wall airfoil comprising a spar and a cover sheet, the spar including a cooling air plenum disposed along an airfoil axis, the cooling air plenum arranged to receive cooling air from the compressor, the airfoil having a pressure side, a suction side, a leading edge, and a trailing edge, the spar including a plurality of standoffs along a pressure side, a leading edge wall, and a leading separator wall each extending away from an outer surface of the spar, the leading edge wall and the leading separator wall extending in a direction along the airfoil axis, the standoffs extending in a direction transversing the leading edge wall and the leading separator wall, the leading separator wall disposed away from the leading edge wall in a direction of the pressure side, wherein a portion of the spar defines an inlet port in communication with the cooling air plenum, a suction-side panel coupled to the leading edge wall, the suction-side panel including a leading end, and a pressure-side panel coupled to the standoffs, the pressure-side panel including a leading end, the leading end of the pressure-side panel and the leading end of the suction-side panel arranged relative to one another to define a leading edge slot, wherein an outlet port is defined by an intersection of a pair of the standoffs and the leading edge slot, the outlet port in communication with the inlet port.
 17. The gas turbine engine of claim 16, wherein the standoffs are disposed radially from another to define a plurality of grooves along the pressure side, wherein the grooves are divided by the leading separator wall into a plurality of body section leading grooves closer in proximity to the leading edge and a plurality of body section grooves closer in proximity to the trailing edge, wherein the inlet port is defined by a portion of the spar along one of the body section leading grooves, wherein a portion of the spar along one of the body section grooves defines a body portion inlet port in communication with the cooling air plenum.
 18. The gas turbine engine of claim 16, wherein a filler material is coupled to an outer surface of the standoffs in the leading edge slot.
 19. The gas turbine engine of claim 16, wherein a pair of strips is coupled to the pressure-side panel and the suction-side panel, extending across the leading edge slot.
 20. The gas turbine engine of claim 16, wherein the leading end of the pressure-side panel defines a first notch, and the leading end of the suction-side panel defines a second notch, the first notch and the second notch being arranged to define an aspect of the outlet port. 